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I was reading this answer and follow up comments: https://physics.stackexchange.com/a/623227/230132

Alessandro says red light can damage a piece of glass if its intensity is sufficient.

I assumed glass was transparent to red light and I also assumed transparent meant there was no interaction.

Both assumptions may be wrong.

So I started to suspect glass to be a less than perfectly transparent medium to red light and as such, given a sufficient intensity, it will heat and burn. Simple math.

Is this the correct explanation though?

I looked for glass absorption and found this page: https://www.koppglass.com/blog/optical-properties-glass-how-light-and-glass-interact

Which includes this graph: Glass absorption

And on this graph it would appear red light with a wavelength longer than 660 nm is not absorbed at all (zero absorption).

700 nm is still visible light, red, and the graph clearly shows zero absorption.

So I am not sure my initial explanation was the right one.

How glass is destroyed by light it does not absorb?

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    $\begingroup$ Looking on a linear scale is not sufficient. For intense enough light, and absorption coefficient of $10^{-6}$ suffices. $\endgroup$
    – Jon Custer
    Mar 25, 2021 at 14:34
  • $\begingroup$ And? What about glass? $\endgroup$
    – Winston
    Mar 25, 2021 at 17:09
  • $\begingroup$ What about it? There likely is measurable absorption in the red, it just doesn't show on that plot. Hit it with enough power and bad things could happen. $\endgroup$
    – Jon Custer
    Mar 25, 2021 at 17:17
  • $\begingroup$ Yeah well that's the whole point of my question. If you can provide a citation or an explanation about glass actually having a non null absorption, that would be an answer. $\endgroup$
    – Winston
    Mar 25, 2021 at 17:19
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    $\begingroup$ Try google.com/… to start, for example. Glasses are not perfect - there are defects. Even in single crystals there are defect states. Long-haul fiber losses may get measured in dB/km, but there are still losses to overcome. $\endgroup$
    – Jon Custer
    Mar 25, 2021 at 17:35

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The extinction coefficient $k$ of glass for visible light is not zero, but approximately $10^{-8}$ (source: https://refractiveindex.info/?shelf=3d&book=glass&page=BK7). This implies that if enough light intensity is shined on a piece of glass, this might be absorbed to the point of heating it up and damaging it.

However, with very high intensities non-linear effects take place and might be dominant for transparent materials. Moreover, they enable non-thermal ablation (for example, see: https://tel.archives-ouvertes.fr/tel-01687375/document)

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  • $\begingroup$ Very interesting contribution. Laser pulses directly breaking atomic bonds. I did not read the entire thesis but I intend to. Thanks. $\endgroup$
    – Winston
    Mar 26, 2021 at 6:47

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